The evaluation of new methodology and its implementation, if proven more efficient or accurate, is the continuing objective of this project. A plate coagulase test which incorporates porcine plasma has proven to be a more sensitive method for detection of S. aureus carriers than the method previously utilized. Further studies to delineate the newly discovered phase variation of H antigens in Serratia marcescens allow more accurate serotyping of these organisms and thus is an aid in epidemiological investigations. Methods for determination of bactericidal and bacteriostatic activity of patient sera are being compared to determine optimal methods. A method of preventing overgrowth of yeasts in tissue cell lines inoculated with patient samples for recovery of viruses is under study. Thus far, Amphotericin B appears to be effective without being toxic to the tissue cell lines.